Leland Yee, a Democratic state senator and candidate for secretary of state in California, has been a longtime champion of gun control. Last week he was arrested on numerous charges, including conspiracy to deal firearms without a license and conspiracy to illegally transport firearms. Yee, a prominent foe of assault weapons, allegedly took bribes to set up a meeting between an undercover agent and an international arms dealer to broker the sale of automatic weapons and shoulder-fired missiles. A lengthy FBI affidavit also describes Yee's ties to a Chinese triad and his desire to help out Islamist militants.

In short, the story makes for what journalists call "good copy."

And yet, so far no reporter has raised the possibility that Yee supported tighter restrictions on guns in order to keep gun prices high and Yee's services in demand. Economist Bruce Yandle popularized the idea of the "Bootleggers and Baptists" coalition. The apocryphal Baptists want to ban alcohol. Bootleggers don't make much money when liquor can be bought legally at a grocery store or bar. So the bootleggers bankroll the Baptists' effort to ban booze.

Now I sincerely doubt that Yee was that clever. The more likely explanation is that he believes in gun control and he's a greedy hypocrite (and maybe not too bright either). The fact that gun-control policies are to his advantage is just a happy coincidence.

What's interesting — and vexing — to me is that this sort of analysis is all the rage when it comes to conservatives and Republicans, and utterly incomprehensible to most journalists when it comes to liberals and Democrats.

Consider the Koch brothers, the billionaire businessmen and philanthropists. The Democratic Party raises vast sums off demonizing the Koch brothers. (Slate's David Weigel reports that fundraising e-mails mentioning the Kochs raised roughly three times as much as those that didn't mention them.) This explains why Sen. Majority leader Harry Reid calls the Kochs "un-American" and liars every chance he gets.

Meanwhile, many media outlets are all too willing to take their cues from Democratic talking points. For instance, the Washington Post recently ran a shockingly shabby story insinuating that the Kochs have a lot to gain from the Keystone pipeline. The story was utterly debunked by John Hinderaker of the website Powerline. (The Kochs have no stake in the pipeline, and even if they did, so what?) But the Post's piece was typical of the media's fascination with the idea that the Kochs' political activities are simply cover for their desire to maximize profits.

Here's the problem. The profit motives of the Koch brothers are by far the least interesting thing about them. Charles and David Koch are worth about $40 billion — apiece! Could they make even more money in a more libertarian America? Who knows? But let's say yes. The idea that they are going to all of this bother just to be worth $50 billion instead of $40 billion is pretty silly when you think about it.

Profit maximization hardly explains why they've given hundreds of millions of dollars to cancer research, hospitals and the arts. And profit lust probably has little to do with why Charles Koch co-founded the nonprofit libertarian think tank the Cato Institute either. It certainly doesn't explain why Charles Koch wrote a book on "market-based management." (Koch's time is more valuable seeking something other than book royalties, of which I'm sure there were few, if any.) Maybe there's a profit motive lurking somewhere in the millions that the Kochs have spent helping GOP politicians, but there are far cheaper and smarter ways for billionaires to buy laws and regulations to their liking.

I have no problem with journalistic skepticism or the search for ulterior motives. I just object to the idea that only Republicans might have them.

Al Gore reportedly left government with a net worth of less than $2 million; he's now worth more than $200 million, in part by profiting from climate policies he lobbies for. Gore surely believes in those policies, but why does he get the benefit of the doubt? GE spent millions on politics in exchange for "green energy" policies that generate billions in profits that wouldn't exist in a free market. Matthew Continetti of the Washington Free Beacon recently chronicled how George Soros and new liberal golden-boy fat cat Tom Steyer have financial interests at stake in their own preferred public policies. And yet they get glowing treatment from the press as idealists sacrificing profit for principles.

The irony is that it'd be in the media's business interest to report on the seedy underbelly of liberal politics, too. But they don't, because they actually do put their liberal principles before profits.

Jonah Goldberg is a fellow at the American Enterprise Institute and editor-at-large of National Review Online. You can write to him by email at goldbergcolumn@gmail.com, or via Twitter @JonahNRO.